Various muscle assistance devices have been proposed as can be found in Japanese patent laid open publication No. 2002-301124, for instance, for the purpose of providing an assisting force to the movement of the leg by using a toque actuator consisting of an electric motor or the like attached to a side part of the hip or knee joint. For instance, such a muscle assistance device enables a person caring a bedridden person to produce a force of the leg which is substantially greater than that the person is normally capable of producing or a person having a walking impediment owing to aging or the like to walk on his or her feet.
Such a conventional walking assistance device is typically provided with an abdomen support member that is wrapped around the abdomen of the wearer and is kept tightly around the abdomen by using Velcro (trademark) tape or a fastening belt in a detachable manner.
However, if the abdomen support member is formed as a cylindrical member like a corset, as it is typically made of relatively rigid plastic material, a considerable effort is required to open one side of the cylindrical member and fit the torso of the wearer into the interior of the cylindrical member. The wearing of the abdomen support member may be facilitated by forming the abdomen support member from more flexible material. However, the abdomen support member is required to have a certain rigidity for the purpose of supporting the actuator. If the abdomen support member lacks a required rigidity, the abdomen support member is unable to support the reaction force of the actuator, and a desired output of the actuator cannot be obtained. Also, such a reaction force causes the actuator to move about with respect to the body of the wearer, and it becomes impossible to control the operation of the actuator in a desired manner.
Furthermore, a human abdomen lacks a skeletal support, and is not able to support a load without causing uncomfortable pressure to the wearer. If the tightness of the abdomen support member is reduced, it would not be able to support the walking assistance device or the reaction of the actuator. Also, the abdomen support member constrains the human abdomen to such an extent that the wearer is hampered from stooping forward, twisting or otherwise moving the body. Also, the width of the human abdomen can vary to such an extent that the walking assistance device of a single size can fit only a small number of wearers and walking assistance devices of a large number of different sizes must be prepared to meet the needs of the wearers of different builds. This leads to an increase in the cost.
Also, as such a walking assistance device sometimes has to be worn unassisted by a disabled person having a limited muscle power, it is highly important that the walking device is light in weight and easy to handle. Additionally, the walking device should be comfortable to wear, and should not unduly hamper the movement of the wearer.